The present invention relates to a natural language processing system, and more particularly to a natural language processing system which involves efficient grammatical rule application processing by limiting grammar rules to those which are previously applicable in accordance with an original text.
A conventional natural language processing apparatus comprises a dictionary and grammar rules for an object language, and a processor for applying the grammar rules.
In the field of natural language processing, both natural language question-answering systems and machine translation systems have been, studied and developed. In order to improve the quality of the process result of translation in the machine translation system, the processing is changing from syntax based processing to semantics based processing, and the amount of dictionary information and processing rules required is increasing significantly.
In order to effectively utilize the huge volume of information, the dictionary may be filed in separate files by domain of subject of the original text and they may be selectively used, or a plurality of translation mechanisms may be provided so that they may be selectively used depending on the original text.
The grammar rules may be grouped by the details of processing and processing details, and the application is controlled for each group to enhance the efficiency of the processing.
A related apparatus is disclosed in JP-A-60-124782, U.S. Pat. No. 4,641,264, and U.S. Ser. No. 61,218 filed June 12, 1987, entitled "Method and System for Language Translation" assigned by the present assignee.
In the prior art, the dictionary or grammar rules are divided by utilizing the characteristic feature of the text and are then selectively used to enhance the efficiency of the processing or, effect the processing suitable to the original text. However, this is not successful because it is difficult to divide the dictionary or grammar rules by the text type, sentence type or domain. Furthermore, even if it is possible, it is not sufficient to solve the problem due to the large volume of information required for high quality processing.
In the natural language processing performed by machine translation, it is necessary to save wasteful processing, and thereby enhance the efficiency, by limiting the dictionary information and grammar rules required for processing the text to only those suitable for the original text.